The human skeletal system provides structure, support, and protection for the body. Phalanges are small, fundamental bones found in the hands and feet. They enable a wide range of functions, from delicate manipulation to stable locomotion.
What is a Phalanx?
A phalanx refers to any of the bones that form the fingers of the hand and the toes of the foot. Phalanges are classified as long bones. Each phalanx is longer than it is wide, possessing a central shaft, a proximal base, and a distal head. Their tubular shape aligns with the definition of long bones, which provide strength, structure, and mobility.
Where Phalanges Are Found
The human body contains a total of 56 phalanges, with 14 in each hand and 14 in each foot. In the hand, each of the four fingers (index, middle, ring, pinky) contains three phalanges: a proximal, a middle, and a distal phalanx. The thumb, however, has only two phalanges—a proximal and a distal one.
Similarly, in the foot, each of the smaller toes has three phalanges (proximal, middle, and distal), while the big toe (hallux) has only two (proximal and distal). The proximal phalanges are positioned closest to the hand or foot, articulating with the metacarpal bones in the hand or metatarsal bones in the foot. The middle phalanges are situated between the proximal and distal bones, and the distal phalanges form the very tips of the digits. Phalanges in the foot tend to be shorter and more compressed compared to those in the hand.
How Phalanges Function
Phalanges function in both the hands and feet. In the hands, these bones enable dexterity, gripping, and fine motor skills. They allow intricate actions such as grasping objects, writing, typing, and playing musical instruments. Joints between phalanges and other hand bones, like the metacarpals, allow for flexion, extension, and some rotation, contributing to the hand’s versatility. The thumb’s ability to oppose other fingers, facilitated by its phalanges, aids a strong and precise grasp. Phalanges also serve as attachment points for muscles and tendons, which are stabilized by ligaments, allowing for controlled and powerful movements.
In the feet, phalanges aid balance, propulsion, and weight-bearing. They provide a stable base of support during activities such as standing, walking, and running. The toes, especially the big toe, assist in the push-off phase of walking and running, propelling the body forward. They also distribute body weight evenly and absorb shock, adapting to uneven surfaces and maintaining stability.
Common Phalangeal Conditions
Phalanges are susceptible to injuries and conditions due to their exposed locations and frequent use. Fractures are common, often resulting from direct trauma, falls, or crush injuries. Fractures can range from simple cracks to comminuted breaks, where the bone shatters into multiple pieces. Injuries to the distal phalanx, the bone at the fingertip, are frequently caused by crush incidents.
Dislocations, where bones are forced out of alignment at a joint, also affect phalanges, often due to sudden force or twisting. The proximal interphalangeal (PIP) joint, in the middle of the finger, is vulnerable to dislocations. Additionally, conditions like arthritis can impact phalangeal joints, leading to pain, swelling, and reduced mobility. An intra-articular fracture can increase the risk of post-traumatic arthritis.